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Topic: Dormer 108 Drill Grinder Resurrection (Read 7974 times)

Several years ago (2009) I bought a very nice Dormer 108 drill grinder, complete with it's mounting cupboard / plinth thingy. All in very nice 'ready to work' condition. Purchase included delivery at seller risk.

All very annoying as I had work for it to do. Seller had literally lain it on a home made pallet and put a bit of plastic 'pallet wrap' round it, and it had been smashed to pieces in the pallet handling system. Not the carriers fault, and the seller did the decent thing and refunded and dragged the carcass away.

No where could I find one quite as nice at an acceptable price, but I did find one without the plinth that sadly had had the 'Hammerite' treatment but was basically sound.

It arrived in a nicely made crate, bolted to it's base - it just needed mounting on something. Well time ticked by, other things took priority, and it sat in it's case until yesterday in one of my containers.

A friend is moving house, and was desperate to store some personal effects safely, so I offered to clear out a load of 'stuff' that should have gone on eBay years ago, and free up half a container, so we started digging. Three wood working dust extractors, a J&S 540 grinder extractor, a 205 litre drum of neat cutting oil and a few other bits and pieces got shifted into the stable temporarily, and put on eBay at 99p starting prices

I have a machinists cabinet that I will probably mount it on, but it'll need putting on castors, and it's current contents redeploying. However I can't get at it at the moment as there is a mountain of cardboard packing waiting for the next bonfire

This probably will be a slow project as it's not top priority - one I'll dip back into several time over quite a period, as I've a few things on the go at the moment

I put a plug on the three phase motor and proved that it did at least work, as that's rather fundamental to this machine. Then I found a diamond wheel dresser and installed it in the swing across dresser holder, and dressed the considerable dishing from the wheel periphery.

So now having decided it was worth carrying on restoring the machine, I started the de-rusting process. I removed the square bar that holds a sliding double ended centre. One end is male, and the other female. They were too rusted to dismantle without doing further damage, so they got dunked in the ubiquitous citric acid bath to clean up. Whilst this was happening I removed the quadrant that is used to set the drill point angle, and that also went in with the other bits.

This let me start to dismantle the square bar assembly without damaging things - it came apart easily except for the male / female centre.

Soaking with 'Plus Gas' followed by thumping with a block of lead eventually released it. Obviously the female centre has vanishingly thin edges and the male has a similarly delicate point, so it could only be thumped with something soft. It did come out, the only damage being to my thumb that leaked an enormous amount of blood

Turns out that there is a firm still stocking some spares for this machine. I thing that I needed was a 'drill protrusion gauge' - only a little rule giving the amount that a drill has to protrude from the holder to get the correct geometry - simple but essential so I've ordered one.

They also had a reasonable copy of the manual. Although I had one with the machine, mine was a photocopy of a photocopy made on a wet day in the middle of a flood, and not much was legible, whereas their one had been cleaned up and re-typed by a nice girl call Claire who had not only photoshopped the parts drawing, but also let me chat her up into discounting their price from atrocious, down to just about manageable

Well that gauge still hasn't arrived, but I've been playing a bit - I've even successfully sharpened a 9 mm drill

However, the protrusion of the drill, which is what the gauge is for, is set by moving the 'tailstock' in or out along a square bar, and it's ever so fiddly as the clamping is with a hex key, and you run out of hands

So I decided to make some knurled clamping screws this morning which have made the setting up far easier. Simple turning and knurling exercise - I 'loctited' screws into blind tapped holes, then parted the screw head off. I'd really have wished to use brass for the one that bears directly on the male / female centre but nowhere could I find a 2 BA brass screw of suitable length, and I was too lazy to thread a bit of brass!

I think long term I'm going to make some form of screw advance for the tailstock, as it's not the most subtle of adjustments as it is.

To operate this grinder, the drill is clamped between jaws, a calculated amount ground off, then the wheel is backed off to let you remove the drill, rotate it 180 degrees, then grind to the same point on this second flank.

To do this reasonably accurately there is a 'stop collar' that can be clamped to physically stop the movement at a particular point, however it's very hard to not over run as the feed handle has much mechanical advantage so it can slide the collar - certainly not precise enough in my opinion.

In the later model the feed handle had a 'friction fit' collar carrying a pointer that could be rotated to show zero, and give you a positive indication that you were where you want to be. No such collar and fidicule line on this one.

I may well modify the machine along those lines in the future, but as a test I decided to rig a dial gauge up to show me when I'd 'arrived'

I have had a magnetically mounted Mitutoyo one that I rescued from an EDM machine I pillaged for spares - it was used to show cutting progress like this one on my own EDM machine, but it was in a sorry state, with a bent needle

Now as Bob KRV3000 wasn't actually locked in a cupboard in the workshop I had to 'have at it' myself, and try and bend it back to a semblance of straightness

So, remove the bezel (retained by spring clips), gently bend the needle with very fine pointed tweezers, and put it back together. I was scared that I was going to break the needle if I fiddled too much, so got it 'reasonably straight' but not perfect